Abstract: The ultraviolet absorption of camptothecin was increased at 254 nm after the lactonic ring opening,and the toxicity of camptothecin was aslo increased. In view of the current determination of camptothecin content at 254 nm,a new method content was explored for determination of camptothecin.Camptothecin had a large absorption at 367 nm from 200 nm to 400 nm,and dimethyl sulfoxide was undisturbed. Therefore,the content of camptothecin was determined at 367 nm and the methodology was investigated. The regression equation is y=0.042 3x+0.013 2,r=0.999 6. The concentration of camptothecin was in a good linear relationship with its absorbance within the range of 4~20 μg/mL. The average recovery of sample was 101.76% and RSD was 0.75%, the results had good reproducibility and more reliable.

Key words: camptothecin, ultraviolet spectrophotometry, content